1. Field of the Invention
The present invention relates to a synchronization system of the cine-projector with a the sound tape reproducer.
2. Description of the Prior Art
In order to reproduce the sound recorded by the magnetic sound recording device in synchronization with the pictures projected by means of a cine-projector, it is necessary to drive the cine-projector and the sound tape reproducer in synchronization with each other, for which purpose various methods have so far been proposed. Namely, the pulse synchronization method used as a synchronization system of the cine-projector with the sound tape reproducer is considered comparatively of high efficiency. In the case of this synchronization method, when the sound is recorded in the sound recording tape while the pictures projected with the same speed as that of the pictures photographed by a cine-camera is observed, one pulse signal is produced per picture and recorded in the control track of the sound recording tape, in such a manner that by means of reproducing the sound signal recorded on another track simultaneously with the control pulse recorded on the control track, this pulse signal is compared with the pulse signals per picture directly obtained from the cine-projector so as to obtain the synchronized operation. In the case of this pulse synchronization system, when the film feeding of the cine-projector is advanced or delayed by more than one picture as compared with the pulses coming from the sound tape reproducer, the restoration is in principle impossible. In order to eliminate such a shortcoming, various methods have been proposed, whereby the synchronization between the film and the sound recording tape is established by counting the difference between the number of the pulses coming from the cine-projector and that of the pulses coming from the sound tape reproducer by means of a counter so as to control the film speed of the cine-projector in such a manner that the counted difference is maintained constant.
In the case of either of the above mentioned methods, the mean electrical power supplied to the film driving motor is controlled in accordance with the film speed of the cine-projector and therefore it is necessary that the film driving motor of the cine-projector of these methods should have a large starting torque and a quick response to the variation of the source voltage, while the moment of inertia of the whole film driving system should be small. In consequence, not only is the design of such device difficult but also the cost of the product is unavoidably increased, which is quite inconvenient.